Many websites allow users to conduct a variety of actions online, such as viewing content, writing reviews, ordering items, purchasing tickets, etc. These websites often present the user with a plurality of actions to choose from and allow the user to select the type of action he would like to perform. Once the action is selected, the website typically redirects the client system of the user to a webpage where the action can be completed. For example, some websites allow users to organize events using an online event management system. An online event management system may allow an event organizer to organize and manage various aspects of an event, such as, for example, managing attendee registrations and selling tickets, promoting the event, and managing attendee check-in at the event. An online event management system may also allow users to view event listings, register for events, and purchase tickets for events. Online systems, such as online event management systems, can typically be accessed using suitable browser clients (e.g., Firefox, Chrome, Internet Explorer).
Some users of an online event management system may attempt to improperly use the system, such as by violating the terms of services of the system or by using the system to commit illegal or improper acts. One type of improper use is creating event listings that contain spam or other improper advertisements. For example, a user may create an online event listing for a fake event and then use the event listing to display an advertisement for a product (e.g., erectile dysfunction drugs, nutraceuticals, pornography). Another type of improper use is creating event listings that include a large number of links to other sites in an attempt to boost rankings at search engines.